Adjustable gas block for an indirect gas operated firearm

ABSTRACT

A firearm including a barrel, receiver, indirect gas system and an adjustable gas block Four positions of adjustment are provided for on the adjustable gas block, each of which provides a different setting to regulate gas flow into the host firearm&#39;s operating system. A position of adjustment is selected based on how the firearm is being used. The provided positions of adjustment are calibrated for the standard use of the host firearm, use of a silencer, use of the firearm under hard or adverse conditions or when it is necessary to increase the firearm&#39;s rate of fire, and to block the flow of gas into the operating system. The provided gas block is designed to function with an indirect gas operating system, but could be adapted for use with a direct gas impingement system as well. Excess gas from the operating system is not vented from the gas block thereby eliminating the generation of additional muzzle flash and sound. No tool is required to manipulate the adjustment mechanism of the gas block.

This is a continuation application of co-pending application, U.S. Ser. No. 12/220,725 filed Jul. 28, 2008, and hereby claims the priority thereof to which it is entitled.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This present invention generally relates to self loading firearms, specifically to gas blocks for self loading firearms which facilitate user adjustment of the gas flow from the barrel into the operating system.

2. Description of the Related Art

The need to regulate the gas flow between the barrel and operating system of a firearm has been a concern since the introduction of autoloading firearms. Gas is generated during the combustion of gun powder present in the cartridges used in modern firearms. This gas expands violently to push the bullet out of the firearm's barrel. These expanding gases are utilized as a means to operate the action of the host firearm. In modern firearms the preferred method of facilitating the function of an autoloading weapon is as follows. A hole is placed thru the barrel, generally on the top. Location of this hole or gas port varies between operating systems. Generally a gas port size is chosen to allow a broad range of ammunition to be utilized while guaranteeing the reliable function of the host firearm. Unfortunately due to varying lengths of barrels, ammunition variance, and other factors it is very difficult to choose a gas port size which universally works under all conditions. A popular way of dealing with these problems is to incorporate an adjustable gas block into the operating system.

An adjustable gas block allows for the flow of gas between the gas port in the barrel and the operating system of the firearm to be increased or decreased based on mitigating factors present at the time of use. These systems typically work by utilizing an oversized gas port with means to adjust the flow of gas into the operating system and by venting the unneeded gases from the barrel into the atmosphere thus generating flash and sound. Further, adjustment of the gas system typically requires a special tool and offers no way for the user to index the system and make adjustments due to mitigating circumstances quickly. Designs such as these are well known in the prior art and can be found on the Belgium F AL, Soviet SVD and the Yugoslavian M76 rifle.

Recent firearm designs such as the FN SCAR rifles have incorporated adjustable gas blocks to be used in conjunction with noise suppressors. Noise suppressors provide a means to redirect and expand the gases generated from the discharge of a firearm so that the resulting flash and sound generated by the firearm is minimized or eliminated. As a result, back pressure is generated forcing more gas into the firearm's operating system. This extra gas, or back pressure increases the firing rate of a weapon during its full auto function, fouls the weapon leading to premature malfunction and to a variety of feeding and extraction problems.

Modern rifle designs such as the FN SCAR Rifles incorporate adjustable gas blocks which have adjustable pre-set positions. Typically two or three positions of adjustment are afforded the user. A reduced gas flow setting on an adjustable gas block is generally present due to military and government agency requirements. Reducing the standard gas flow is desirable when a silencer is to be used. Silencers increase back pressure and the cyclic rate of the host firearm. By reducing the amount of gas directed to the operating system under normal circumstances, the silencer, with the increased pressure it generates, should not affect the weapon's operation significantly. While designs with an adjustable gas block mitigate the potential problems associated with the increased back pressure and fouling a noise suppressor generate, gases are still vented out of the gas block thus generating flash and sound. Generating flash and sound from the gas block is counter productive to the function of the silencer which is attempting to reduce the flash and sound from the muzzle of the host firearm.

The present invention offers several advantages over the prior art. Four positions of adjustment are provided for. Position one offers a “standard” flow of gas. This position is optimized for the firearms barrel length and caliber. Position two reduces the flow of gas into the indirect gas operating system so that with the addition of a silencer the indirect gas operating system is still receiving an equivalent amount of gas as was being provided by position one when no silencer was being utilized. Position three blocks the flow of gas between the barrel gas port and the indirect operating system. This position optimizes the sound reduction capability of an attached noise suppressor. Position four increases the amount of gas being communicated to the operating system so that the firearm may operate properly while dirty or when under powdered ammunition is being utilized. Each of the aforementioned positions of adjustment are indexed with a spring and ball detent, and are pre-set at the factory. No tool is required to rotate the adjustment cylinder into one of the four positions. There is no vent in the gas block which allows for excess gas or un-burnt powder to exit.

SUMMARY OF THE INVENTION

Accordingly several objects and advantages of the present invention are

(a) To provide the user an indexing means to adjust the flow of gas into the operating system of a firearm.

(b) To provide a device which restricts the flow of gas into the operating system without venting excess gas from the gas block.

(c) To provide an adjustment mechanism which does not require the use of special tools.

(d) To provide an adjustable gas block that may be utilized with an indirect gas system.

(e) To provide an adjustable gas block with a means to provide gas that is in excess of what is required to help the weapon function in adverse conditions or with underpowered ammunition.

In accordance with one embodiment of the present invention, a firearm is provided comprising a receiver, a barrel, an adjustable gas block for an indirect gas operated firearm and an indirect gas system. The adjustable gas block is fixedly secured to the barrel and aligned with the gas port hole located thereon. A rotating cylinder provides an indexing, adjustment means for the gas block. By rotating the provided cylinder the flow of gas between the barrel and the indirect gas system is either increased or decreased. Four position of adjustment are afforded the user: A standard gas flow, suppressed gas flow, no gas flow, and an adverse conditions gas flow setting. For adverse conditions the gas flow is increased over what the host weapon would typically require to compensate for a dirty operating system.

Still further objects and advantages will become apparent from a consideration of the ensuing description and drawings.

DESCRIPTION OF THE DRAWINGS

The novel features believed to be characteristic of the present invention, together with further advantages thereof, will be better understood from the following description considered in connection with the accompanying drawings in which a preferred embodiment of the present invention is illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention.

FIG. 1 is a side perspective view of an adjustable gas block for an indirect gas operated firearm in accordance with the present invention;

FIG. 2 is an exploded view thereof;

FIG. 3 is a partial cutaway view of the nozzle assembly and adjustment knob;

FIG. 4 is a side cutaway view of the adjustable gas block for an indirect gas operated firearm;

FIG. 5 is a side perspective view of an autoloading rifle, with the adjustable gas block for an indirect gas operated firearm in place.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The adjustable gas block for an indirect gas operated firearm 1 is designed to provide four positions of adjustment, each of which affects the flow of gas from the barrel gas port into the operating system of the host firearm. The herein disclosed device is designed for an indirect gas operating system, it should be noted however that this device is not limited to such operating systems and in fact could be utilized with a gas impingement operating system such as is found on the M16 family for firearms.

Turning now to the drawings in which like reference characters indicate corresponding elements throughout the several views, attention is directed to FIG. 1 which illustrates the preferred embodiment of the herein proposed invention. The adjustable gas block for an indirect gas operated firearm 1 is a replacement for a standard gas block, well known in the prior art, for an autoloading firearm. The adjustable gas block for an indirect gas operated firearm 1 is comprised of a housing 10, adjustment knob 20, nozzle assembly (piston) 30, and a front sight 60.

In FIG. 2, there is illustrated an exploded view of the adjustable gas block for an indirect gas operated firearm 1 and all of its components. The gas piston block 10 has a piston receiving channel 13 which is located above the barrel receiving channel 12. Near the distal end of the gas piston block 10 is located a placement 14 for the adjustment knob 20. Located along the bottom of the gas piston block 10 are two thru pin placements which are utilized to secure the unit as a whole about a barrel. A front sight 60 is provided for on the distal end of the gas piston block 10 along with a bayonet lug 70.

The preferred embodiment piston 30 consists of a proximal end, middle and a distal end. On the proximal end is an end wall 33 which blocks the proximal opening entirely. A thru pin bore 34 is present proximate the proximal end. Near the middle of the piston 30 are the connecting member 39, the radial flange 40, and the diameter-reducing transition portion 41. At the distal end is a nozzle 31 which provides an opening into the interior of the piston 30.

The adjustment knob 20 has a series of slots 25-28 which run transverse to the axis of the piston void 29 located in the center of the adjustment knob 20. The slots 25-28 are located on the front of the adjustment knob 20. A thru pin bore 24 is present on the exterior of the adjustment knob 20 and is designed to receive a thru pin 21.

In FIG. 3 there is illustrated a view of the adjustment knob 20 and the nozzle assembly 30. The nozzle assembly 30 is partially cut away to reveal the three gas ports which are 45 degrees offset from one another proximate the connecting member 39. Gas port one 35, gas port two 36, and gas port three 37 are each unique in size. These gas ports 35-37 all intersect in the center of the nozzle assembly 30.

FIG. 4 illustrates a cutaway view of the adjustable gas block 1. The gas piston block 10 houses a spring 22 and ball detent 23. A porthole 44 thru the gas piston block 10 is in communication with the nozzle assembly 30. The nozzle assembly has a bore 38 which is in communication with the nozzle 31 and the porthole 44 located in the gas piston block 10. The adjustment knob 20 is secured about the nozzle assembly 30 by means of a thru pin 21 placed into the thru pin bore 24.

FIG. 5 illustrates a perspective view of a firearm receiver 90 connected to a barrel 101 utilizing a removable rail 91 which incorporates an indirect gas operating system 100 and the gas piston block 10.

As used herein, the word “front” or “forward” corresponds to direction right of the gas piston block 1 (i.e., to the right as shown in FIGS. 1 thru 5); “rear” or “rearward” or “back” corresponds to the direction opposite the direction of the gas piston block 1 (i.e., to the left as shown in FIGS. 1 thru 5); “longitudinal” means the direction along or parallel to the longitudinal axis of the gas piston block 1; and “transverse” means a direction perpendicular to the longitudinal direction.

The adjustable gas block 1 receives a portion of a firearm barrel 101 inside of the gas piston block 10 in the barrel receiving channel 12. Two thru pin placements 15 spaced apart along the bottom of the gas piston block 10 receive two thru pins which prevent rotation or longitudinal movement of the adjustable gas block 1 along the length of the barrel 101. The piston receiving channel 13, located above the barrel receiving channel 12, has an opening which runs parallel to the bore line of the firearms barrel 101. Between the front site 60 and the piston receiving channel 13 is a placement 14 which houses the adjustment knob 20. The adjustment knob 20 has a centrally located void 29 which receives the proximal end of the nozzle assembly 30. The nozzle assembly is 30 housed within the piston receiving channel 13 and void 29 located within the adjustment knob 20. Thru pin bore 24 is located on the adjustment knob 20 and another thru pin bore 34 is located on the proximal end of the nozzle assembly 30. These two thru pin bores are aligned and a thru pin 21 is utilized to secure both the nozzle assembly 30 and the adjustment knob 20 together. A spring 22 and ball detent 23 are located under the piston receiving channel 13 where the ball detent 23 interfaces with the four indexing notches 25-28 located about the distal or rear end of the adjustment knob 20.

Four positions of adjustment are provided for. Three gas ports 35-37 are provided to regulate the flow of gas into the operating system 100. Nozzle assembly 30 and adjustment knob 20 are in operational communication. Toggling the adjustment knob 20 rotates the nozzle assemble 30 into one of four positions. One position 25 provides the standard flow of gas, for use when the weapon is being utilized in its factory configuration with no accessories. Another position 26 reduces the flow of gas for use of a silencer with the host firearm, well known in the prior art. Still another position 28 is provided which introduces more gas than is needed under normal circumstances, such as when the firearm is utilizing under powered ammunition or the weapon is fowled with un-burnt powder and debris. Finally, a position 27 which blocks the flow of gas from the porthole 44 in the gas piston block 10 from entering the nozzle assembly's 30 internal nozzle 38 and preventing the operating system of the firearm from cycling the weapon. The adjustment knob 20 is rotated by the user to select the desired flow of gas. Spring 22 and ball detent 23 prevent unintentional movement of the adjustment knob 20 by interfacing with the notches 25-28 located on the face of the adjustment knob 20.

When a firearm is discharged expanding gases travel down the barrel 101 and a small amount of this excess gas is vented through a gas port located at the top of the barrel 101. This gas travels through the porthole 44 located in the gas piston housing 10. If the adjustment knob 20 and thereby the nozzle assembly 30 are rotated in such a manner as to allow the flow of gas into the operating system 100, one of three gas ports 35-37 will be in direct communication with the porthole 44 located in the gas piston housing 10. Depending on the use of the firearm the user will utilize the adjustment knob 20 to select the appropriate gas setting. Gas will enter the nozzle assembly 30 through one of the three gas ports 35-37 located near the proximal end of the nozzle assembly 30, travel thru the internal nozzle 38 and exit the nozzle 30 thereby entering the indirect gas operating system 100 of the host firearm.

When the weapon is dirty, or under-powered ammunition is being utilized, the adjustment knob 20 and thereby the nozzle assembly 30 are rotated so that gas port three 35 is in communication with the porthole 44 located in the gas block 10. When a silencer is being utilized, thereby increasing the flow of gas into the operating system 100, gas port one 36, which is smaller in diameter, should be chosen. This prevents the gas operating system 100 from becoming over-gassed and causing extraction problems, or increased wear of the operating systems 100 components. Under normal firing conditions, gas port two 37 is chosen which provides the necessary flow of gas into the operating system 100 for the firearm to operate under normal firing conditions.

In sum, an adjustable gas block is provided for an autoloading firearm which utilizes and indirect gas operating system. Four pre-set positions are afforded the user of this device. Gas settings which are optimized for suppressor use, hard environments, dirty weapons or when firing under ideal circumstances are provided for. A position which prevents the flow of gas into the operating system is provided for. This system does not vent excess gas from the gas block into the atmosphere around it. Instead excess gas is trapped within the barrel and vented from the muzzle where a flash hider or silencer might allow the gasses to expand and cool.

Another embodiment of the adjustable gas block could eliminate the increased gas flow setting or the setting which blocks of the flow of gas.

Still another embodiment of the adjustable gas block could be adapted to work with a direct gas impingement system such as found on M16 style rifles. The nozzle assembled could be modified to receive the gas tube found on such system and thereby regulate the flow of gas from the barrel into the operating system.

While the above drawings and description contain much specificity, these should not be construed as limitations on the scope of the invention, but rather as an exemplification of one preferred embodiment thereof.

Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents. 

1. A firearm utilizing an adjustable gas block comprising: a receiver; a barrel connected to the receiver, said barrel having a gas port; a gas operating system; a nozzle assembly having a front end, back end, and internal void with means to communicate with the barrel and gas operating system through a plurality of ports which are spaced about the front end, said back end is received by a portion of the gas operating system, the back end has an opening in operational communication with said gas operating system; a gas block housing having a receiving channel for a portion of the barrel to be contained therein, a cylindrical bore which runs parallel to the axis of the barrel located above the receiving channel with a port in communication with the barrel, the cylindrical bore containing a portion of the nozzle assembly therein; a rotatable knob which both receives and rotates the nozzle assembly within said cylindrical bore, said rotatable knob being configured to retain and rotationally restrain the nozzle assembly within said cylindrical bore.
 2. The firearm using the adjustable gas block of claim 1 wherein said nozzle assembly has at least two ports about its front end which can be selectively placed into communication with said barrel gas port.
 3. The firearm using the adjustable gas block of claim 1 wherein said nozzle assembly has at least three ports which can be selectively placed into communication with said barrel as port.
 4. The firearm using the adjustable gas block of claim 1 wherein said nozzle assembly has four selectable positions of adjustment, three of said selectable positions placing a port into communication with said barrel gas port.
 5. The firearm using the adjustable gas block of claim 1 wherein each port which comprises said plurality of ports has a unique sized opening.
 6. The firearm using the adjustable gas block of claim 5 wherein said rotatable knob has a plurality of selectable positions, all but one of said selectable positions correlating to position one of the plurality of ports of the nozzle assembly into communication with said barrel gas port, one of said selectable positions rotating said nozzle assembly into a position such that no gas port is in communication with the barrel gas port.
 7. An improvement in an indirect gas operated firearm having a receiver, a stock connected to an end of the receiver, a barrel connected to a front of the receiver, a handguard connected to the barrel and a gas operating system, the improvement comprising: a gas block structured to be secured about the barrel, said gas block having a gas block housing with a barrel receiving channel for receiving a portion of the barrel therein, the housing also having a gas nozzle receiving channel with a portion of the gas nozzle contained therein; said gas nozzle receiving channel having a void which houses a rotatable adjustment knob, the adjustment knob being in cooperation with the gas nozzle and, by rotation thereof, regulating the flow of gas between said barrel and said gas operation system; and a gas nozzle that is in operational communication with the barrel and the operating system, the gas nozzle communicating with the barrel through a series of ports located about a periphery of said gas nozzle, said adjustment knob when rotated placing at least one port, at a time, into communication with the barrel, the portion of said gas nozzle in communication with the operating system being received by said operating system and having an opening which vents gas, originating from the barrel, into said operating system.
 8. The improvement as in claim 7, wherein each of said series of ports, located on said gas nozzle, has a uniquely sized opening and serves to regulate the flow of gas into said indirect operating system.
 9. (canceled)
 10. The improvement as in claim 8, wherein said gas block has an opening that houses a spring and a detent, said spring and detent working in conjunction with a series of notches present on said adjustment knob to prevent the unintentional rotation of said knob. 